Roof-mounted ventilation air duct

ABSTRACT

A ventilation air duct is anchored to a flat roof of a building by means of a ballast material, such as gravel. The weight of the ballast material is selected to secure the duct to the roof without any other fasteners.

TECHNICAL FIELD

This invention generally relates to the field of ventilation air ductsand more particularly, to modular ducts with easy and fast installationproperties.

BACKGROUND

Ventilation air ducts are usually made of sheet metal that carry cooledor heated air to all rooms of a building. It is well known in the artthat ventilation ducts often have to be installed on the roofs becauseit is inconvenient to have them inside the building for spacelimitations, cost or other reasons. Exposed outside ducts are expensiveto mount. Sections of ventilation air ducts must be fabricated andhoisted on the roof or they may have to be built on site. It is alsowell known that once on the roof, the sections are mounted on bracketstighten on a system of mounting brackets and/or lay on wooden beams on aflat roof. The anchoring of the sections is time consuming since themounting brackets and/or beams need to be installed first and then thesections need to be anchored to the mounting brackets and/or beams.

It would be highly desirable to be provided with a ventilation air ductsystem which is installed in a faster and more efficient way as knownduct systems.

SUMMARY

One aim of the present invention is to provide a ventilation air ductcomprising light-modular sections that can be easily hoisted andinstalled on a flat roof of a building.

Another aim of the present invention is to provide cost-effective solarair preheating.

In accordance with the present invention, there is provided aroof-mounted ventilation air duct adapted to be connected to aventilation unit on a flat roof of a building comprising a plurality ofduct sections adapted to be connected end to end in fluid flowcommunication to form a fluid passage for allowing air to flowtherethrough, wherein at least some of said plurality of duct sectionsare provided with a ballast receiving portion, and a ballast materialadapted to be disposed on said ballast receiving portion for anchoringthe duct sections to the flat roof under the weight of the ballastmaterial, the duct sections and the ballast material having a combinedweight which is selected to render said duct sections immovable to sidewinds on the flat roof of the building.

In accordance with a further general aspect of the present invention,there is provided a building comprising: a flat roof; a ventilation unitmounted on said flat roof; and a roof ventilation air duct seateddirectly on said flat roof and operatively connected to the ventilationunit, the ventilation air duct comprising a plurality of duct sectionsadapted to be connected end-to-end in fluid flow communication to form afluid passage for allowing air to flow theretrough, wherein at leastsome of said plurality of said duct sections have a seat within thefluid passage for receiving a ballast material, the ballast materialanchoring the duct sections to the flat roof, the duct sections and theballast material having a combined weight which is selected to rendersaid duct sections immovable to side winds on the flat roof of thebuilding.

In accordance with a still further general aspect of the presentinvention, there is provided an air duct section adapted to be connectedto a ventilation unit of a building comprising: a body extending from afirst open end to a second open end and forming a fluid passage forallowing air to flow theretrough, said first and second open ends beingadapted to be connected in fluid flow communication with first andsecond similar air duct sections, respectively; a seat within thepassage; and a ballast material adapted to be disposed on said seatwithin the fluid passage such as to be in contact with the air flowingtherethrough, the duct section and the ballast material having acombined weight which is selected to anchor by gravity the duct sectionto an underlying support surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, showing by wayof illustration, a preferred embodiment thereof, and in which:

FIG. 1 is a schematic perspective view of a ventilation system mountedon a flat roof section of a building;

FIG. 2 is a schematic perspective view of a section of a roof-mountedventilation air duct adapted to be connected to similar duct sectionsand comprising a top lid that can be opened to place a ballast materialin the duct section for anchoring the duct section to the roof; and

FIG. 3 is a cross-section of a roof-mounted ventilation duct having aperforated solar panel for preheating the air before being dispensedinto the building.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a ventilation system 10 mounted on a flat roof R of abuilding B. The ventilation system 10 generally comprises a conventionalventilation unit 12 adapted to draw fresh air into the building B viaventilation air duct 14. The ventilation unit 12 is also coupled withsupply ducts 15. The ventilation air duct 14 comprises a plurality ofduct sections 14 a, 14 b, 14 c . . . and 15 a, 15 b, 15 c, adapted to beserially connected in fluid flow communication. The duct sections 14 a,14 b, 14 c . . . and 15 a, 15 b, 15 c can be made out of galvanizedsteel, stainless steel and fiberglass-polyester or other suitablematerials for exterior ductwork. Best results are obtained withUV-resistant polymer casings with insulation inside.

As shown in FIG. 2, each duct section 14 defines an air passage 16. Theduct sections 14 a, 14 b 14 c . . . 15 a, 15 b, 15 c can be of anysuitable cross-sectional shape, but preferably of low profile. Accordingto the illustrated embodiment, the duct sections have a rectangularcross-section formed by top, bottom and side walls 18, 20 and 22. Thebottom wall 20 can be provided with built-in legs 20 a for supportingthe duct sections directly on the flat roof R. The duct sections 14 a,14 b, 14 c . . . 15 a, 15 b, 15 c are connected end-to-end by means ofany suitable attaching device 23, such as clips or the like. The topwall 18 can be provided in the form of a lid hinged to one of the sidewall 22, thereby allowing the lid to be pivoted between open and closedpositions. A lock (not shown) is provided to selectively maintain thelid in its closed position. The lid can be opened to provide access toair passage 16, A ballast material 24, for instance in the form of bulkmatter, is placed inside the air passage 16 on the inner surface of thebottom wall 20. The bottom wall 18 thus acts as a seat for receiving theballast material 24. The weight of the ballast material 24 is selectedto firmly anchor the duct section on the building roof R. The ballastmaterial can be provided in the form of gravel, which is readilyavailable and can be handled easily.

The duct sections 14 a, 14 b 14 c . . . 15 a, 15 b, 15 c and the ballastmaterial 24 have a combined weight which is selected to render the ductsections immovable to side winds on the flat roof of the building. Thisadvantageously provides a fastener-less anchoring system. The ductsections 14 a, 14 b, 14 c . . . 15 a, 15 b, 15 c are laid on the roof Rwithout further anchoring which does not cause damages on the roofsurface. This advantageously obviates the need for the installation of aduct support on the building roof (i.e. no roof modification). It isnoted that only some of the duct sections can be provided with anopenable lid. The ballast material 24 does not necessarily need to beplaced in each and every section.

The ballast material 24 is preferably provided as a thermal mass placedin heat exchange relationship with the duct sections 14 a, 14 b, 14 c .. . 15 a, 15 b, 15 c and the air flowing therethrough in order to storeheat during daytime and release it in to the air flowing through the airpassage 16 over night or, during the summer season, store coolnessovernight and release it during the day. The thermal mass (i.e. theballast material) acts as a temperature damper during days when solarradiations fluctuate, particularly on partly cloudy days. The thermalmass may store sensible heat, as would be case with gravel, or latentheat, as would be the case if a phase-change material were used. Theballast material 24, when placed inside the air passage 16, also acts asa turbulator agent to increase heat transfer to the air flowing throughthe duct sections 14 a, 14 b, 14 c . . . 15 a, 15 b, 15 c However, it isunderstood that the ballast material 24 could be placed outside of theduct sections 14 a, 14 b and 14 c and 15 a, 15 b, 15 c. For instance,each duct section 14 a, 14 b and 14 c, 15 a, 15 b, 15 c could beprovided on opposed longitudinal sides thereof with integral gutter-likechannels (not shown) to provide a seat for receiving the ballastmaterial and anchor the duct sections to the building roof R. Accordingto this example, the duct sections could be provided without any lid.The ballast material could also be otherwise attached to the ductsections as long as the duct sections are secured to the roof by theweight of the ballast material.

FIG. 3 shows one duct section 14 d having a triangular cross-section andan equator-facing solar collector panel 28 integrated as one of thesidewall of the duct section for absorbing the incident solar radiation.The triangular shape is advantageous in that it prevents water or snowaccumulation on top of the duct sections. The triangular shape alsorenders the duct sections less prone to movement due to side winds bydeflecting the lateral incoming outside air.

The collector panel 28 can be hinged to the other side wall 22 or thebottom wall 20 of the duct section 14 d to provide access to theinterior of the duct section and allow pouring of the ballast material24 inside the duct section. The collector panel 28 can be coated on theoutside with a solar radiation absorbing material, such as dark paint.Far more desirable than dark paint would be a “selective coating” withhigh absorption for solar radiation and little infra-red heat emissionat temperatures occurring at the collector panel on a sunny day, to keeptotal energy losses low.

Alternatively, the collector panel 28 can have a plurality of inlet airopenings over its surface, or can be made of glazing or transparentmaterial to facilitate heating of the ballast material 24 and, thus, thepreheating of the air drawn through the duct sections. This effect isparticularly beneficial during autumn and spring, and even summer, whenpreheating of the air may not be wanted during daytime but needed in theevening or later in the night.

Such a perforated air heating panel can be used with an inclination ofpreferably 70 degrees above horizontal in Canadian climates or adjustedfor optimal energy output in other parts of the world. The outside airis being heated as it travels through the perforated plate. Thisadvantageously allows to preheat the air before being dispensed into thebuilding B.

Solar energy utilization of the duct sections 14 a, 14 b, 14 c, 14 d . .. can be useful in an industry where large amounts of outside air are tobe heated to a set point as high as possible, as frequently as possible.An example of such an industry is a building admitting over 10 000 cubicfeet per minute (cfm) of fresh air which must be heated to 70° F. ormore, seven days a week, twenty-four hours per day.

In another non-illustrated embodiment, the sections of the air duct maycomprise two sections, one through which incoming fresh air is drawninto the building and one through which the outgoing air from thebuilding is being expelled. Both sections are separated by a thinconductive plate, such as a sheet metal of steel or aluminum. Thisallows using the roof-mounted conduits as a heat exchanger.

The ventilation ducts 14 and 15 can be easily installed by hoisting thelightweight duct sections on the building roof R using a crane or thelike. The sections are preferably designed so that they are stackable,in order to hoist more than one piece at a time with the crane. Thesections are then laid down directly onto the roof deck and connectedtogether end-to-end. Then, the ballast material 24 is poured into theduct sections 14 a, 14 b, and 14 c . . . in order to anchor the ductsections to the roof and resist wind dislodgement.

The present ventilation duct anchoring method have several advantagesthat can be generally summarized as follows: quick installations, nodamage to roof surface, high immovability, thermal stability, better airtightness than ducts made on site, easy access to duct interior, heatstorage (thermal mass or by means of phase-change material), solar gainapplication (integrated collector panel), watershed design (triangularshape).

While the invention has been described with particular reference to theillustrated embodiments, it will be understood that numerousmodifications thereto will appear to those skilled in the art. Forinstance, the present duct anchoring method is not limited to roofapplications. Accordingly, the above description and accompanyingdrawings should be taken as illustrative of the invention and not in alimiting sense.

While the invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodifications and this application is intended to cover any variations,uses, or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come within known or customary practice within theart to which the invention pertains and as may be applied to theessential features hereinbefore set forth.

What is claimed is:
 1. A roof-mounted ventilation air duct adapted to beconnected to a ventilation unit on a flat roof of a building comprisinga plurality of duct sections adapted to be connected end to end in fluidflow communication to form a fluid passage for allowing air to flowtherethrough, wherein at least some of said plurality of duct sectionsare provided with a ballast receiving portion, and a ballast materialadapted to be disposed on said ballast receiving portion for anchoringthe duct sections to the flat roof under the weight of the ballastmaterial, the duct sections and the ballast material having a combinedweight which is selected to render said duct sections immovable to sidewinds on the flat roof of the building.
 2. The roof-mounted ventilationair duct of claim 1, wherein at least a plurality of said duct sectionsfurther comprise a lid to provide access to the fluid passage and theballast receiving portion, the ballast receiving portion being locatedwithin the duct sections.
 3. The roof-mounted ventilation air duct ofclaim 1, wherein said ballast material is a thermal mass which is inheat exchange relationship with the duct sections one placed on saidballast receiving portion.
 4. The roof-mounted ventilation air duct ofclaim 3, wherein said ballast material is dispensed in the fluid passagesuch as to be in direct contact with the air flowing therethrough. 5.The roof-mounted ventilation air duct of claim 1, wherein at least someof said duct sections are provided on an equator-facing outside surfacewith a collector panel adapted to absorb incident solar radiation. 6.The roof mounted ventilation air duct of claim 5, wherein the collectorpanel has a plurality of inlet air openings.
 7. The roof-mountedventilation air duct of claim 5, wherein the collector panel comprisestransparent material.
 8. The roof-mounted ventilation air duct of claim4, wherein the collector panel is selectively moveable between a closedposition in which the collector panel is supported in an inclinedposition and an opened position in which the collector panel providesaccess to the interior of an associated duct section.
 9. Theroof-mounted ventilation air duct of claim 2, wherein said lid is asolar panel.
 10. The roof-mounted ventilation air duct of claim 1,wherein each of the duct sections is adapted to be supported directlyonto the flat roof by means of built-in legs provided on the bottomsurface of each duct sections.
 11. The roof-mounted ventilation air ductof claim 5, wherein the duct sections have a generally triangularcross-sectional shape.
 12. The roof-mounted ventilation air duct ofclaim 1, wherein at least some of said plurality of duct sections have asheet metal separating the fluid passage in said duct sections in afirst section where incoming air is drawn into the building and a secondsection where outgoing air from the building is expelled, wherein saidfirst and second sections are in heat exchange relationship.
 13. Abuilding comprising: a flat roof; a ventilation unit mounted on saidflat roof; and a roof ventilation air duct seated directly on said flatroof and operatively connected to the ventilation unit, the ventilationair duct comprising a plurality of duct sections adapted to be connectedend-to-end in fluid flow communication to form a fluid passage forallowing air to flow therethrough, wherein at least some of saidplurality of said duct sections have a seat within the fluid passage forreceiving a ballast material, the ballast material anchoring the ductsections to the flat roof, the duct sections and the ballast materialhaving a combined weight which is selected to render said duct sectionsimmovable to side winds on the flat roof of the building.
 14. Thebuilding of claim 13, wherein at least some of said duct sectionsfurther comprises a lid to provide access to the seat.
 15. The buildingof claim 13, wherein said ballast material is a thermal mass being inheat exchange relationship with the air flowing through the fluidpassage.
 16. The building of claim 13, wherein at least some of saidplurality of duct sections have an air heating panel coated on anoutside surface thereof with a solar radiation absorbing material. 17.The building of claim 16, wherein the air heating panel is perforated.18. The building of claim 14, wherein said lid is a solar panel.
 19. Anair duct section adapted to be connected to a ventilation unit of abuilding comprising: a body extending from a first open end to a secondopen end and forming a fluid passage for allowing air to flowtheretrough, said first and second open ends being adapted to beconnected in fluid flow communication with first and second similar airduct sections, respectively; a seat within the passage; and a ballastmaterial adapted to be disposed on said seat within the fluid passagesuch as to be in contact with the air flowing therethrough, the ductsection and the ballast material having a combined weight which isselected to anchor by gravity the duct section to an underlying supportsurface.
 20. The duct section of claim 19, further comprising a lidbetween said first and second end of said body to permit direct accessto the seat.
 21. The duct section of claim 20, wherein said ballastmaterial is a thermal mass.
 22. The duct section claim 21, furthercomprising an air heating panel integrated to said body.